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Our scope of road design is
no longer confined to just the traveled way (pavement) or even the
right-of-way. Rather, it now encompasses the right-of-way and all its
access features (driveways, intersecting streets). Context-sensitive
design, now the goal of good road design, includes all of these roadway
features and also the adjoining land development.
The first step in the design
process, establishing the design controls, is where the “big decisions,”
which largely determine the character of the road, are made. Previously,
these decisions were made by specialist technicians, who then proceeded with a
design based on the controls. Previously, stakeholders were not invited
into the process until detailed elements were being fitted to the design.
The transect
arranges all the possible settings of a road into a few distinct categories,
ranging from the most rural to the most urban. With the setting clearly
defined, road designers can develop plans that fit and improve the value of
their surrounding.
Transect points define the
different types of settings along a road corridor. This set of 7 points,
illustrated graphically, established the range of desired settings in
Cross-section elements are
the design details that establish much of the road’s appearance and
character. The design of all cross-section elements should vary,
according to the setting (“transect point”) of the specific segment of road
being designed. The failure to observe the distinction and settings
accounts for much of the “one-size fits all” inappropriateness of many
recent road designs.
Building placement, while
not a roadway design element, has a critical impact on the character of the
road. The conventional suburban building placement, with the buildings
deeply set back and with parking adjacent to the road, permanently relegates
the road to a blighted suburban strip commercial character. Further, this
character ensures high operating speeds (50-60 mph) for vehicles, further
undermining any “main street” or “town center” atmosphere. The same development,
arranged so that buildings front the road and parking is concealed in the rear
(i.e., same amount of buildings and parking) produces a road with fundamentally
different character and low (20-30 mph) operating speeds for vehicles.
These conditions permit attractive character, such as main streets or town
centers.
Conventional Development
Pattern: Until recently, the pattern for almost all new growth in
The “traditional”
pattern of development is both the historical pattern of development (for
example, Avondale and Chatam village centers) as well as the pattern now
advocated for “smart growth” development. In this development
pattern, land uses are arranged along a street and block pattern, with
different land uses immediately adjacent to each other. Most travel
between different land uses is made on the local, highly connected street
network.
The travel pattern on the
conventional suburban pattern of streets focuses all travel onto the existing
arterial highway (in
In the traditional or “smart growth” development pattern, much of the local travel between land uses is accommodated on local network, and therefore does not require the use of the existing arterial road, such as Route 41 in Chester County. Around three-quarters of all travel is local in nature, and could therefore avoid the use of arterial highways, at least in peak hours. Providing more local network, to accommodate local trips, is often the most satisfactory approach to improving travel conditions for local residents.
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